Hydrotesting to warranty limits
Hydrotesting to warranty limits
(OP)
I have some potentially defective 10" pipe that I need to use and need to develop the hydrotest criteria for. I say it is potentially defective because some 12" pipe that we bought from the same mill had some long seam defects that were discovered while hydrotesting. The mill has given us extended warranty on all the pipes, so I want to throw out the following question:
Should we test this pipe to 100% SMYS (using a yield plot) to ensure that this pipe meets the warranty criteria, or test to 95% SMYS which is the maximum test pressure (at low point) required to achieve the required MAOP.
This pipe is 273.1 mm OD x 4.8 mm WT, Gr. 359, ERW, Cat II - CSA Z245.1M and we are working under the CSA Z662-07 code. MAOP = 8619 kPa
Should we test this pipe to 100% SMYS (using a yield plot) to ensure that this pipe meets the warranty criteria, or test to 95% SMYS which is the maximum test pressure (at low point) required to achieve the required MAOP.
This pipe is 273.1 mm OD x 4.8 mm WT, Gr. 359, ERW, Cat II - CSA Z245.1M and we are working under the CSA Z662-07 code. MAOP = 8619 kPa





RE: Hydrotesting to warranty limits
If the mill is giving extended warranty coverage to 100%, I'd do a 100%, but that's just my idea. They didn't do you any favors. Provided you don't have a new Merceds in the driveway this morning
**********************
Kermit http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy"
....
http://virtualpipeline.spaces.live.com/
RE: Hydrotesting to warranty limits
Or something like that...if I did it right...
I would try 100% NDE on all long seams without pressure testing if the pipe hasn't shipped yet. If the pipe has shipped you could say that you were, in essence, going to proof test it at 100% or 95% SMYS in the field and that they would be on the hook for any ensuing warranty claims, but I doubt the Seller would agree to that. Further, you would likely be faced with a non-routine application with the Regulatory Authority for any such test (above 80% x SMYS), who would ask what the technical justification for it would be. If the justification is that you have doubts about the integrity of the long seams, be careful how you word that.
Regards,
SNORGY.
RE: Hydrotesting to warranty limits
In ASME B31.8 ss 845.214 states,
So, for a US gas pipeline B31.8 is saying to use the pressure registered at the high elevation as the value to divide by the location factor to arrive at the MAOP. Low point pressure is irrelevant to determining MAOP. It additionally states that that pressure shall not be higher (at the high point) than yield pressure, which would also allow that a pressure at a low point actually be higher than yield pressure, as so provided for in (5).
Does CSA limit the test pressure as you have said?
He didn't mention any elevation head .. specifically.
**********************
Kermit http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy"
....
http://virtualpipeline.spaces.live.com/
RE: Hydrotesting to warranty limits
In CSA Z662, yield plots are required for test pressures that would stress the pipe to 100% SMYS or greater.
RE: Hydrotesting to warranty limits
The 12" pipe that had the long seam defects was purchased at "discount rates" and we did not have mill inspectors. The mill did foot the bill for the cost of repairs and the UT tool run after repairs were made. We are doing digs on the 12" pipe this year to confirm the UT tool data.
Doing the test to 100% SMYS does require a yield plot, but I am reluctant to take the test up to yield. I figure there is not much point stretching the pipe if I don't have to. The test to 100% would prove the pipe meets the specifications, but only at the low points in each test section.